Studies of the physiological and pathophysiological characteristics of the stable hypertrophied myocardium will be pursued. This period of time concentrates on the studies of the coronary blood flow regional distribution, the characteristics of thallium uptake and imaging, and segmental function in the hypertrophied myocardium at rest and under stress. The effects of coronary ischemia on the hypertrophied heart are also to be studied ad characterized in terms of segmental changes as well as regional blood flow, and the means of myocardial protection during bypass in the hypertrophied heart will be explored. BIBLIOGRAPHIC REFERENCES: Geha, A.S.: Coronary and Cardiovascular Dynamics and Oxygen Availability During Acute Normovolemic Anemia. Surgery 80:47-53, 1976. Wolfson, S.L., Gehan A.S., Hammond, G.L., Langou, R.N. and Cohen, L.S.: Preliminary Report: Modification of Intra-aortic Balloon for Pressure Measurement, Contrast Injection and Guide Wire Passage. American Journal of Cardiology 39:260, 1977.